OsLSD1.1 is involved in the photosystem II reaction and affects nitrogen allocation in rice

Nitrogen (N) is an essential nutrient element for plants; however, high N accumulation often leads to a decrease in photosynthetic nitrogen use efficiency (PNUE). In rice (Oryza sativa L.), well-developed aerenchyma is formed to promote oxygen transport from the shoot to the root tips as an adaptation to submerged and oxygen-deficient environment. Total N concentrations were increased in the rice root by changes in O₂ levels in the rhizosphere. However, few reports have focused on how aerenchyma formation-related genes participate in photosynthesis and affect nitrogen allocation in rice. In this study, we found that OsLSD1.1, located in the chloroplast, cell membrane, and nucleus, may be involved in the photosystem II reaction and affect chloroplast development. OsLSD1.1 knockout was found to significantly reduce the quantum efficiency of the PSII reaction center (ΦPSII). Furthermore, we observed that the nitrogen accumulation decreased in the grain of OsLSD1.1 mutants. RNA-Seq transcriptome analysis revealed that OsPEPC3, OsPsbR1, OsNRG2, OsNRT1.5A, OsNRT1.7, and OsAMT3;2 were downregulated in m12 compared with N-WT (wild-type Nipponbare), which may be a reason that photosynthesis and nitrogen transport were inhibited. Taken together, our findings demonstrated that OsLSD1.1 may be key in plant growth, photosynthesis, and nitrogen allocation in rice. Our results may provide theoretical support for the discovery of key genes for nitrogen physiological use efficiency.